Are Roof Insulation Boards Waterproof?

PIR foam will shrug off the odd splash or brief shower, but it isn’t waterproof. Prolonged exposure to rain, or any detailing where water can sit on the board, should be avoided. Keep the sheets dry on site and install them in a way that keeps moisture out of the build-up.

Which Roof Board Suits My Roof?

Start with the basics: Roof shape: Flat or pitched.Waterproof Layer: Torch-on bitumen, single-ply, tiles, metal, etc.Target U-Value: What the drawings (or Building Control) demand.Traffic Load: Will the roof carry plant or regular footfall?Moisture And Fire Performance: Any special requirements? For many flat roofs: Warm Roof (Insulation Under The Waterproofing): PIR is a common, cost-effective choice.Inverted Roof (Insulation Above The Membrane): XPS copes better with constant wetting. On pitched roofs, PIR works well both between and over rafters. When in doubt, run the options past your architect or building-control officer.

Do I Need A Vapour-Control Layer (VCL)?

Nearly always, yes. Warm, moist indoor air can drift into a roof build-up, cool, and condense, reducing insulation performance and risking timber decay. A VCL on the warm side of the board blocks that moisture path.Foil-faced PIR often doubles as the VCL; tape the joints and seal around penetrations.If the board has no built-in barrier, fit a separate VCL membrane and lap, tape, or seal every seam.

Can Any Board Take A Torch-On Membrane?

No. The flame used in torch-on work can scorch or melt standard PIR and XPS sheets. Use boards that carry a torch-on-compatible facing, typically a bitumen-coated glass tissue or mineral surface, and always check the manufacturer’s data sheet before ordering.

Roof Insulation Boards and Panels

50mm Kingspan GreenGuard XPS Extruded Polystyrene Insulation 300kpa (6m2/Pack)

Roof Insulation Board

50mm Kingspan GreenGuard XPS Extruded Polystyrene Insulation 300kpa (6m2/Pack)

30mm Kingspan GreenGuard XPS Extruded Polystyrene Insulation 300kpa (10.5m2/Pack)

100mm Kingspan GreenGuard XPS Extruded Polystyrene Insulation 300kpa (3m2/Pack)

165mm Celotex XR4165 PIR Insulation Board 2400mm x 1200mm

50mm Kingspan Kooltherm K107 Pitched Roof Insulation Board 2400mm x 1200mm (6/Pack)

120mm Kingspan Kooltherm K107 Pitched Roof Insulation Board 2400mm x 1200mm (2/Pack)

200mm Celotex XR4200 PIR Insulation Board 2400mm x 1200mm

150mm Kingspan Thermaroof TR27 Flat Roof Insulation Board 1200mm x 1200mm (2.88m2/Pack)

75mm Kingspan Kooltherm K107 Pitched Roof Insulation Board 2400mm x 1200mm (4/Pack)

25mm Kingspan Kooltherm K107 Pitched Roof Insulation Board 2400mm x 1200mm (12/Pack)

40mm Kingspan GreenGuard XPS Extruded Polystyrene Insulation 300kpa (7.5m2/Pack)

60mm Kingspan GreenGuard XPS Extruded Polystyrene Insulation 300kpa (5.25m2/Pack)

80mm Kingspan GreenGuard XPS Extruded Polystyrene Insulation 300kpa (3.75m2/Pack)

120mm Kingspan Thermaroof TR27 Flat Roof Insulation Board 1200mm x 1200mm (5.76m2/Pack)

100mm Kingspan Thermaroof TR26 Flat Roof Insulation Board 2400mm x 1200mm

25mm Kingspan Thermaroof TR27 Flat Roof Insulation Board 1200mm x 600mm (8.64m2/Pack)

120mm Kingspan GreenGuard XPS Extruded Polystyrene Insulation 300kpa (2.25m2/Pack)

70mm Kingspan Kooltherm K107 Pitched Roof Insulation Board 2400mm x 1200mm (4/Pack)

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